Zoom lens drive system for lens shutter type of camera

Abstract

A zoom lens for a camera having a between-the-lens shutter includes a motor for moving the lens along an optical axis in forward and rearward directions. A switch is operable by an operator to control operation of the motor for moving the lens from an initial position on the axis to a final stationary position that establishes the focal length of the lens. Control apparatus is responsive to the setting of the switch for operating the motor such that movement of the lens from its initial position to its final position always ends after the lens travels to its final position in a predetermined direction.

We claim: 
     
       1. A zoom lens shutter camera comprising: a photographic optical system and a finder optical system which is independent of said photographic optical system, said photographic optical system having an optical axis and including a zoom lens, said zoom lens having a plurality of lens groups which are supported within said camera, said zoom lens being movable: (a) within a zooming range in order to vary the focal length of said zoom lens; (b) to an accommodated position in which said zoom lens is located closer to a film plane surface in said camera than when said zoom lens is within said zooming range; and (c) within a transition range located between one end of said zooming range and said accommodated position;   a zoom lens position detection system capable of detecting the position of said zoom lens;   a motor for driving said zoom lens;   a manually operable zoom switch for selectively forwardly or reversely rotating said motor to respectively move said zoom lens in first and second opposite directions along said optical axis when said zoom lens is within said zooming range;   a main switch for selectively forwardly or reversibly driving said motor to move said zoom lens from a position within said zooming range to said accommodated position, or from said accommodated position to a position within said zooming range; and   a motor control system for supplying electrical power to said motor when said motor is driving said zoom lens;   wherein, when said main switch is operated so as to move said zoom lens to said accommodated position, (i) said zoom lens is driven by said motor when said position detection system determines that the zoom lens is positioned within said transition range, and (ii) said motor stops driving said zoom lens when said apparatus determines that said zoom lens is located at said accommodated position.   
     
     
       2. A zoom lens shutter camera in accordance with claim 1, wherein said position detection system comprises a binary code system for identifying the location of said zoom lens as being within said zooming range, within said transition range, or at said accommodated position. 
     
     
       3. A zoom lens shutter camera in accordance with claim 1, wherein said position detection system includes a code sheet for detecting the position of said zoom lens. 
     
     
       4. A zoom lens shutter camera in accordance with claim 3, further comprising a plurality of conductive brushes for selectively contacting conductive lands on said code sheet. 
     
     
       5. A zoom lens shutter camera in accordance with claim 3, further comprising a zoom code encoder for receiving zoom code data from said code sheet. 
     
     
       6. A zoom lens shutter camera in accordance with claim 1, further comprising a driving ring which is rotatably driven by said motor, said lens groups being positioned within said driving ring. 
     
     
       7. A zoom lens shutter camera in accordance with claim 6, wherein said driving ring comprises a cam ring. 
     
     
       8. A zoom lens shutter camera comprising: (a) a photographic optical system comprising a zoom lens moveable along an optical axis of said system to vary the focal length of said zoom lens within a zooming range defined by a wide angle position and a telephoto position;   (b) a finder optical system which is independent of said photographic optical system;   (c) a motor which is operable to drive said zoom lens along said optical axis in forward and rearward directions between and including said wide angle position and said telephoto position;   (d) a zoom switch assembly for selectively rotating said motor in opposite directions, said zoom switch assembly being selectively positionable into a first ON position in which said motor forwardly drives said zoom lens, a second ON position in which said motor rearwardly drives said zoom lens, and into an OFF position in which said motor does not drive said zoom lens; and   (e) a control system which rotatably drives said motor forwardly when said switch assembly is in said first ON position, which rotatably drives said motor reversely when said switch assembly is in said second ON position, and which stops said motor when said switch assembly is in said OFF position, such that when said switch assembly is moved from one of said ON positions to said OFF position, rotation of said motor is reversed, prior to stopping, to move said zoom lens to a final position in a direction opposite to the direction in which said lens is normally moved when said switch assembly is positioned at said one ON position.   
     
     
       9. A zoom lens shutter camera in accordance with claim 8, wherein said zoom switch assembly comprises a single actuating member slidable among said first and second ON positions and said OFF position. 
     
     
       10. A zoom lens shutter camera in accordance with claim 8, wherein said one ON position is said first ON position. 
     
     
       11. A zoom lens shutter camera in accordance with claim 8, wherein said zoom switch assembly comprises separate telephoto and wide-angle actuators for selectively positioning said zoom switch assembly into said first and second ON positions. 
     
     
       12. A zoom lens shutter camera including a zoom lens drive system, said camera comprising: (a) at least one photographic zoom lens adapted to be positioned in a plurality of different focal length positions along a photographic optical axis;   (b) a finder optical assembly which is independent of said zoom lens;   (c) a reversible motor capable of moving said zoom lens along said optical axis, in forward and rearward directions, into said plurality of focal length positions;   (d) a switching assembly which is actuatable by an operator, said switching assembly including at least one zoom switch which is positionable into two distinct ON positions to identify the direction and movement of said lens towards said plurality of focal length positions, and which is positionable into a neutral, OFF position, in order to stop said motor; and   (e) a control system which is responsive to said switching assembly to operate said motor such that movement of said zoom lens from an initial position, determined by the position of the zoom lens when the operator begins to operate said switch assembly, to a final position determined by said switch assembly, always ends after the zoom lens travels to its final position in a predetermined direction which is independent of the direction identified by said switching assembly.   
     
     
       13. A zoom lens shutter camera in accordance with claim 12, wherein one of said focal length positions is a telephoto position, and wherein another of said focal length positions is a wide angle position. 
     
     
       14. A zoom lens shutter camera in accordance with claim 12, wherein said zoom lens is positionable at a wide angle position representing a relatively short focal length and a telephoto position representing a relatively long focal length, said predetermined direction being a forward direction with respect to said telephoto position. 
     
     
       15. A zoom lens shutter camera according to claim 12, including a system for focusing said zoom lens on a subject to be photographed as a function of the distance of the subject from the camera, and a system for focusing said zoom lens only after the zoom lens arrives at said final position. 
     
     
       16. A zoom lens shutter camera in accordance with claim 12, wherein said control system includes: (a) a position detecting apparatus which detects the presence of said zoom lens at one of said focal length positions;   (b) a direction detecting apparatus which detects the directional movement of said zoom lens; and   (c) a logic apparatus, responsive to operation of one of said switching assembly, said position detecting apparatus, and said direction detecting apparatus, said logic apparatus comprising a system which operates the motor in a direction such that the zoom lens will move towards a final position identified by said switching assembly, at least until said position detecting apparatus detects the presence of said zoom lens at said final position, said logic apparatus thereafter either: (1) stopping operation of the motor, if the lens arrives at the final position moving along said predetermined direction; or   (2) continuing operation of the motor for a given period, if the lens arrives at said final position moving in a direction opposite to said predetermined direction, and thereafter reversing the directional movement of said lens by causing said motor to move the lens in said predetermined direction.